1. Field of the Invention
The present invention relates to a cervical clamp for preventing reflux of a fluid medium injected into a uterus.
2. Brief Description of the Prior Art
There are various medical procedures which involve the injection of a fluid medium into the uterus. Included in this category are hysteroscopy and hysterosalpingography. In hysteroscopy, a thin sheath is inserted through the cervix into the uterine cavity. The sheath contains fiber optics that transmit light for viewing the uterine cavity and may also contain a biopsy, electrocautery or other instrument. With hysterosalpingography, x-rays are taken after a radiopaque dye has been injected through the cervix to outline the uterine cavity and fallopian tubes, often as part of an examination for causes of infertility.
Fluids are injected into the uterus in other procedures such as endometrial ablation and chromopertubation. In endometrial ablation, a solution is held in the uterus for visualization while the lining of the uterus is removed by treatment with laser or electrical energy or, possibly, by heating the solution injected into the uterus. Chromopertubation is similar to hysterosalpingography but done during a laparoscopic examination wherein the cervix is sealed and a dye is injected to verify the patency of the fallopian tubes.
The practice of the above procedures involves sealing the walls of a cervical canal around a sheath delivering the fluid medium such that the medium does not reflux around the sheath's exterior back through the cervix. Numerous devices have been developed to prevent reflux, but they are either difficult to use or limit the shape and diameter of the sheath passing through the cervix, or they restrict the movement of instruments in the uterus once the sheath has been inserted into the cervical canal and/or interfere with palpitory information available to the operating physician.
For example, a tenaculum with two pivotally mounted arms with inwardly directed spikes has been used in hysteroscopic examination. The gripping action is performed solely by the spikes digging into the cervix and pressing it against the sheath, causing bleeding, trauma and pain for the patient. It is sometimes necessary to use two of these tenacula, filling the vagina and further limiting the movement of the sheath and other instruments which may pass through it.
Other devices sealably engage a cone (called an "acorn") with the outside opening of the cervical canal by means of a sliding vacuum cup connected to a vacuum port. Once the vacuum cup is evacuated, it seals with the cervix, pushing the acorn into the outside opening. One major problem with this type of device is that there is frequently a mismatch between the size of the cup and the size of the cervix. The device also limits movement of the sheath in the vaginal canal and requires a source of vacuum which may be noisy, such as a vacuum pump, or leak, such as a vacuum syringe.
An inflatable balloon for inflation in the cervical canal or a pair of balloons for inflation, one on the outside opening of the canal and one on the inside have been provided on the sheath inserted through the cervical canal. Once the sheath has been inserted and the balloon(s) inflated, the sheath cannot be further moved. In addition, the sheath carrying the balloon(s) must be relatively large so it is difficult for the operating physician to insert it through the cervical canal.
The best device heretofore known to the applicant is a tenaculum described in The Journal of Reproductive Medicine, Vol. 31, No. 7, July 1986 and in U.S. Pat. No. 5,059,198. The tenaculum described therein purses the cervix against the sheath by squeezing it into an oval at opposite side edges. A better seal might be obtained if the cervix were compressed radially against the sheath, the previous tenaculum, not providing this action.